Saturday, May 22, 2010

Pastured Dairy may Prevent Heart Attacks

Not all dairy is created equal. Dairy from grain-fed and pasture-fed cows differs in a number of ways. Pastured dairy contains more fat-soluble nutrients such as vitamin K2, vitamin A, vitamin E, carotenes and omega-3 fatty acids. It also contains more conjugated linoleic acid, a fat-soluble molecule that has been under intense study due to its ability to inhibit obesity and cancer in animals. The findings in human supplementation trials have been mixed, some confirming the animal studies and others not. In feeding experiments in cows, Dr. T. R. Dhiman and colleagues found the following (1):

Fat from ruminants such as cows, sheep and goats is the main source of CLA in the human diet. CLA is fat-soluble. Therefore, skim milk doesn't contain any. It's also present in human body fat in proportion to dietary intake. This can come from dairy or flesh.

In a recent article from the AJCN, Dr. Liesbeth Smit and colleagues examined the level of CLA in the body fat of Costa Rican adults who had suffered a heart attack, and compared it to another group who had not (a case-control study, for the aficionados). People with the highest level of CLA in their body fat were 49% less likely to have had a heart attack, compared to those with the lowest level (2).

Since dairy was the main source of CLA in this population, the association between CLA and heart attack risk is inextricable from the other components in pastured dairy fat. In other words, CLA is simply a marker of pastured dairy fat intake in this population, and the (possible) benefit could just as easily have come from vitamin K2 or something else in the fat.

This study isn't the first one to suggest that pastured dairy fat may be uniquely protective. The Rotterdam and EPIC studies found that a higher vitamin K2 intake is associated with a lower risk of heart attack, cancer and overall mortality (3, 4, 5). In the 1940s, Dr. Weston Price estimated that pastured dairy contains up to 50 times more vitamin K2 than grain-fed dairy. He summarized his findings in the classic book Nutrition and Physical Degeneration. This finding has not been repeated in recent times, but I have a little hunch that may change soon...

27 comments:

I suspect that grain fed cows in WP's time were not given vitamin K supplements, a practice which is commonplace now, from what I understand, so I'm not sure there's more K2 in grass fed dairy than grain fed dairy.

Also, many "paleo" people consume inordinant amounts of dairy fat (upwards of 1000 calories per day in some cases). I am not sure that much CLA is good. Over a threshold, natural trans fats have a similar effect on certain surrogate markers as do industrial trans fats. Perhaps those markers are meaningless, but perhaps not...

That's interesting, I didn't know modern dairy cows are supplemented with K1. That could potentially change the relation between pasture feeding and butterfat K2 as you said. I'd be surprised if they received as much fortified K1 as they would on pasture though, since greens are extremely rick in K1.

Hi Kathryn,

I don't really know if the differences between raw and pasteurized milk are meaningful, but they might be. Pasteurization destroys enzymes that aid in milk's digestion and assimilation. You could say that of any food, although perhaps milk is different because it's specifically designed to be digested. On principle, I think raw milk is probably better, but I don't know whether or not the differences are meaningful in terms of long-term health.

I think it's actually menadione (K3) that used more often in animal feed. I remember reading somewhere that very little K3 ends up consumed by people as the cows convert it very quickly. It's probably not great for cow longevity but it does seem to prevent vit K deficiency in them.

So the bottom line is that good dairy is beneficial (considering your other posts on dairy as well), but there are too many nutrients to control in order to pinpoint what is doing what. But, Ned's comment is interesting, since butter has many of the same nutrients as cheese.

A bit off topic--do pasture-raised animals have an altered total pufa content, or is only the type changed?

So when you have an injury where there is lots of blood flow or blood pooling and lots of inflammation, without enough K2 the body starts depositing calcium into soft tissues.

You see this a lot with injuries such as ankle sprains -- the bony areas start enlarging by calcification which severely limits mobility permanently in some cases.

Similarly, this is a big worry with type II or type III strained/torn muscles where there is a lot of inflammation and blood pooling.

Calcific tendonitis is another issue.

The high degree of blood flow to the area (of course because they're arteries) and the inflammation lead to the calcification of the plaques. This of course leads to atherosclerosis and calcification of the plaque -- macrophages & oxLDL-triglycerides + oxLDL-cholesterol.

Their outcomes in both mice (vegetarian) and pigs (omniverous) were that after administration of Bifido breve (CLA-producing, antiCandidal strain, one of several 'healthy human baby' strains), alteration of the microbiota showed changes in adipose fatty acid profiles: more EPA + DHA in adipose and more CLA in livers.

I don't breastfeed *haa* or eat or drink much fermented stuff so I started b. breve 1X per wk from BOTH Now Probiotics-10 and iFlora multi; iFlora is small enough for kids to swallow. Subjectively I think I feel better. Commercial CLA is a synthetic patented molecule which I have complete reservations about.

Actually, CLA is a naturally occurring trans fatty acid, which in this case is OK (not in the same league as as man-created trans fats). I know, I know: the more you know, the more you know you don't know ;-).

Regarding your question about the pufa content of pasture fed dairy, the first reference by Stephen in the above post, table 3, shows that the fat in milk from cows fed 100% on pasture is 1.4% omega-6, 2.0% omega-3, while cows fed 1/3 pasture is 4.3% omega-6, 0.8% omega-3.

In the Rotterdam and Epic studies, references 3,4 and 5 of Stephen's post, the main determinant of vitamin K2 intake intake was cheese intake. Fermentation of aged cheese increases the K2 content tenfold.

In the Epic study, two thirds of K2 intake was from cheese. About 40% of the K2 was MK(4), the K2 naturally present in diary fat. Most of the rest of the K2 was MK(5)to MK(9) from the fermentation of cheese.

So regarding vitamin K2, milk, butter and eggs are good, but aged cheese is best. Raw aged cheese also is readily available, legally, as long as it has been aged 60 days or more. Raw milk cheese has much the same benefits as raw milk, but has a longer shelf life and is easier to ship.

Natto, the fermented soy product eaten in some parts of Japan, has a high level of vitamin K2, mostly MK(7), that results from fermentation. It has been found that intake of MK(7) results in increased serum level of MK(7) AND MK(4), apparently due to degradation of MK(7) to MK(4). So it seems there is no need to worry whether the vitamin K2 from fermentation has the same benefits as that naturally present in dairy.

I thought you might be interested in this study:"Biomarkers of milk fat and the risk of myocardial infarction in men and women: a prospective, matched case-control study."http://www.ncbi.nlm.nih.gov/pubmed/20484449

I love, love, LOVE Dr. Price's work. What a genius. He's from Ohio, and there's a debate going on now about which famous Ohioan should have a statue placed in Washington, DC to represent the state. Most people are saying John Glenn or some athlete or another. I think they may need to pay more attention to this guy. Had people paid more attention to his work in the 1930s, the eugenics movement might have been killed off a lot faster, and we wouldn't be seeing this metabolic syndrome epidemic going on now.

Dr. Atkins is from here too. I live in the city where he was born. That's another possible candidate as far as I'm concerned, but that's not going to happen any time soon...

Interesting study though. You know, it could be both the CLA and the K2. For all we know, maybe they even work together for our benefit.

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